I have had a concussion and can really sympathize. Since I am older, the ricochet effect is stronger I think and I do still have symptoms a few years later, but I think a younger person generally has a better chance at recovery in full. Screens are a big problem!!
Find out who the 504 coordinator is at your school and see if she can have a 504 plan. Of course she is entitled to tutoring at home after a certain amount of time, but that is not always the best path, since the tutor comes at a fixed time and symptoms fluctuate- and she should probably be resting anyway.
I would think that at first all school work could be postponed and she could have some sort of “incomplete” or set of extensions so she can finish in the summer.
One of mine has some serious health issues that took her out of school for months but her GPA did not suffer nor did her learning, ultimately. I went to a lawyer for suggestions (not adversarial with the school, they just didn’t know how to handle it). So this is what we did: every day, every teacher filled out a sheet with homework assigned, work done in class, (with notes or class and homework materials attached), grades missing (to keep organized), and any quizzes or tests attached. She took one exam at home. Every day, we picked up a package of these papers at the nurse’s office (nurse collected them from teachers).
This way, my kid could go in and out of school with ease, so she would go up for one class, come home, then go up for another class or extracurricular.
I would note that at first we tried getting the packages on days she was not in class, or for classes she missed, but that did not work: teachers could not remember to notice. It was the principal’s own idea to do it for every class every day so teachers would get into the routine of it daily.
Since hers was a long term situation, we also met with the principal and he waived the requirement that she attend all day in order to participate in extracurriculars. She sometimes did play rehearsal on days when she didn’t get to school. This helped with the isolation and had social benefits. The principal understood this, thank heavens.
She gradually returned to normal attendance after many months.
We made health a priority, as you are. Many appointments and therapies. But she managed to do very well with admissions and is now happily in a PhD program in a field she loves. Things will get better! We adults can take a long term view and it can be hard to convey that to teens, but it sounds like you are doing a great job 